1. Field
Embodiments of the present invention generally relate to apparatus and methods for supporting a semiconductor substrate during fabrication. More particularly, embodiments of the present invention relate to apparatus and method for controlling the apparatus with adjustable edge control provision.
2. Description of the Related Art
Electronic devices and integrated circuits commonly are fabricated by a series of process steps in which layers are deposited on a substrate and the deposited material is etched into desired patterns. The process steps commonly include physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), and other plasma processing. Specifically, a plasma process requires supplying a process gas mixture to a vacuum chamber, and applying electrical or electromagnetic power (RF power) to excite the process gas into a plasma state. The plasma decomposes the gas mixture into ion species that perform the desired deposition or etch processes.
One problem encountered with plasma processes is the difficulty associated with establishing uniform plasma density over the substrate surface during processing, which leads to non-uniform processing between the center and edge regions of the substrate. One reason for the difficulty in establishing uniform plasma density involves natural electrical, gas flow, RF delivery, grounding paths, and thermal skews due to asymmetry in the physical process chamber design. Such skews not only result in naturally, azimuthal, non-uniform plasma density, but also make it difficult to use other processing variables or “knobs” to control center-to-edge plasma uniformity.
Furthermore, additional space or mounting provisions within or around the plasma chamber are always desired for better uniformity control so that flexibility for future retrofit with different hardware sets may be increased when different issues or skew pattern are found. Insufficient space for future processing chamber retrofit may result in significant redesign when adding future hardware sets, thereby adversely increasing manufacture cost. Incompatibility of the existing and future (e.g., retrofit) chamber parts may also lose flexibility for minor chamber parts replacement or rearrangement, resulting in rigidity of the plasma chamber design which increases the difficulty for future hardware enhancement.
Therefore, a need exists for a plasma processing apparatus that improves electrical, gas flow, and thermal symmetry as well as providing flexibility for future hardware enhancements.